DE2455287C3 - Use of water-in-oil emulsifiers - Google Patents

Description

The invention relates to the use of novel water-in-oil emulsifiers, which are excellent aids especially in the cosmetics industry.

Water-in-oil emulsifiers are required to incorporate an aqueous phase into an oil or fat in such a way that the latter has an easily spreadable consistency (ointments, creams, lotions or make-up). Finally, they are also required in pharmacy for the application of active ingredients. Such water-in-oil emulsifiers are also used in technology, namely in emulsion polymerization, in water-in-oil dispersions of polymers. Up to now, water-in-oil emulsifiers have been used, for example, as wool fat (lanolin) and lanolin/alcohol derivatives. Fatty acid esters of hexitols, e.g. sorbitan sesquioleate, as well as fatty acid monoglycerides, β-entaerythritol fatty acid esters, fatty alcohol citrates and fatty alcohol oxyalkylates. DE-AS 20 23 786, for example, discloses: For example, glycerol esters of wool wax acids have become known for this purpose.

Although these water-in-oil emulsifiers are suitable for specific applications, they often have disadvantages. They are often not stable to acids or alkalis. Lanolin esters and fatty acid esters, for example, are not saponification-stable, which limits their use in the cosmetics industry, for example, since the unpleasant smell of the free fatty acids occurs after saponification. In addition, the emulsions are often only moderately stable and cannot be universally used for all substances under consideration.

Water-in-oil emulsifiers are known from DE-AS 12 20 441, which are obtained from, among other things, '. chain alcohols by reaction with preferably 2 to 3 moles of epichlorohydrin. However, these emulsifiers are also not completely satisfactory in terms of their emulsifying power.

The aim of the present invention was to develop water-in-oil emulsifiers that are not only stable against all possible chemical influences, but that can also be used in a universal manner.

The solution to the problem is defined in claims 1 and 2. The emulsifiers to be used are characterized by their preparation.

The preparation can also be conveniently carried out by carrying out the acid-catalyzed addition of epichlorohydrin and then splitting off hydrogen chloride from the chlorohydrin using solid, powdered alkali hydroxide. In all cases, the desired water-in-oil emulsifiers are produced.

The starting materials for production are fatty alcohols and synthetic long-chain alcohols with 10 to 22 carbon atoms, such as oleyl alcohol, stearyl alcohol, cetyl alcohol, linolenyl alcohol, myristyl alcohol, lauryl alcohol, tallow fatty alcohol, the technically produced alcohol mixtures such as C ₂ O - to C ₂₂ -alcohol, C ₁₆ - to C ₁₂ -alcohol, C ₁₇ - to C ₁₉ -oxo alcohol and C ₉ - to C _n -oxo alcohol. Of course, mixtures of alcohols, especially the naturally occurring alcohols mentioned above, can also be used.

The alcohols are then reacted in the first step with epichlorohydrin, whereby a molar ratio of Aikchc! to E'^chicrh'^dpn ~ ^- :c I ^- 0 5 b ^: s 1 5 vcrzu"·""*·" ^1-t •»»'»si*

Examples of polyhydric alcohols containing 2 to 6 carbon atoms and 2 to 6 hydroxyl groups or their monoethers derived from the fatty alcohols defined above are: diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,2,4-butanetriol, glycerin, trimethylolpropane, sorbitol, sorbitan. Neopentyl glycol, pentaerythritol and as ethers the monoethers of the alcohols mentioned, preferably glycerin with stearyl alcohol, oleyl alcohol and other alcohols defined above, e.g. 2,3-ethylhexylpropanediol. The fatty alcohol ethers of glycerin can, for example, be formed during the reaction by opening the epoxide ring of the fatty alcohol glycidyl ether, but they can also be produced in a known manner from fatty alcohol and glycidyl or by hydrolysis of the fatty alcohol glycidyl ether and react with the fatty alcohol glycidyl ethers as such or in a mixture with the polyhydric alcohols mentioned above.

Acidic or alkaline catalysts can be used for the reaction of glycidyl ethers with polyhydric alcohols. Of the acidic catalysts, Lewis acids such as boron fluoride are particularly suitable.

etherate, boron fluoride phosphoric acid, boron fluoride acetic acid, boron fluoride hydrate, boron fluoride alkyl glycol etherate, tin tetrachloride, zinc chloride, titanium tetrachloride or aluminum chloride, then inorganic acids such as sulfuric acid; alkali hydroxides, alkali alcoholates or alkaline earth alcoholates are conveniently chosen as alkaline catalysts.

Of course, different glycidyl ethers can also be reacted in a mixture or one after the other with the polyhydric alcohol or a mixture of polyhydric alcohols.

The reaction is conveniently carried out once by adding the acid catalyst to the polyhydric alcohol under an inert gas atmosphere at temperatures of 5 to 50°C, preferably 20 to 30°C, and adding the appropriate molar amount of glycidyl ether over a period of 5 to 60 minutes, maintaining a reaction temperature of between 50 and 80°C. The reaction mixture is left at the selected temperature for 2 to 8 hours and kept in mechanical motion. The catalyst is then neutralized and the emulsifier is obtained directly. If alkaline catalysts are selected, reaction temperatures of 150 to 220°C are generally maintained, but otherwise the procedure is analogous. The emulsifiers to be used according to the invention are excellently suited to the production of water-in-oil emulsions in the cosmetics sector. Cosmetic preparations, for example skin creams, generally contain long-chain paraffins such as Vaseline, possibly a wax component such as ozokerite and ointment, then glycerides of fatty acids, i.e. fats, and preservatives, as well as perfume oil and water. The entire system is kept in the desired phase distribution by the emulsifiers.

The emulsifiers to be used according to the invention can be identified by parameters such as density, viscosity, color number and color indices.

They are generally liquid substances that have thawing points, depending on the starting substance, between 15 and 60°C, densities between 0.910 and 0.950, viscosities at 50°C of 150 to 300 mPa/sec, color numbers between 2 and 11 and refractive indices measured at 50°C between 1.4000 and 1.5000.

The following examples of production and use explain the invention; parts mentioned are parts by weight, unless expressly stated otherwise. Here, parts by volume are related to parts by weight as milliliters are related to grams.

Manufacturing examples

example 1

96.4 parts (1.05 mole parts) of glycerine are mixed with 10.4 volume dividers* of boron hydroxide diethyl etherate (47%) in a round-bottom flask under nitrogen at 25°. Then 340 parts (1.05 mole parts) of oleyl glycidyl ether are added dropwise over a period of 40 minutes, keeping the reaction temperature at 60 to 65° C. The reaction mixture is stirred for 4 hours at 65° C. The acid catalyst is neutralized or separated using a basic ion exchanger. A light yellow, clear liquid with very good water-in-oil emulsifying properties is obtained.

Example 2

_ 60.4 parts (0.57 mole parts) of 1,2,4-butanetriol are mixed with 0.3 parts by volume of boron fluoride etherate under nitrogen at 25°C. 200 parts (0.57 mole parts) of oleyl glycidyl ether are added to this mixture over a period of 50 minutes, keeping the reaction temperature at 60 to 65°C. The mixture is initially stirred for 4 hours at 65°C, then the temperature is increased to 100° C and held at this temperature for 3 hours. Small amounts of unreacted butanetriol are separated off and a clear, light yellow liquid with very good emulsifying properties is obtained.

Example 3

115 parts (1.25 molar parts) of glycerine, 400 parts (1.25 molar parts) of C ₁₇ C _oxoalcohol glycidyl ether and 3.5 parts of sodium methylate are heated to 190 to 200° C under a nitrogen atmosphere and with vigorous stirring and kept at this temperature for 5 hours. After separating off a small portion of unreacted glycerine, a colorless solid substance with good water-in-oil emulsifying properties is obtained.

55 1 ·

26.8 parts (0.2 molar parts) of trimethylolpropane and 129.6 parts (0.4 molar parts) of oleyl glycidyl ether are mixed with 0.8 part of sodium methylate under a nitrogen atmosphere and the mixture is heated to 200° C for 5 hours with vigorous stirring. After the reaction has ended, a light yellow, clear liquid with very good water-in-oil emulsifying properties is obtained.

Example 5

28 parts (0.3 mole parts) of glycerine, 97.2 parts (0.3 mole parts) of oleyl glycidyl ether and 0.7 parts by volume of BF ₃ phosphoric acid (45%) are heated to 100°C under nitrogen and with vigorous stirring for 5 hours. The mixture is allowed to cool and the acid catalyst is separated off by treatment with a basic ion exchanger. A clear, light yellow liquid with very good water-in-oil emulsifying properties is obtained.

Example 6

26 parts (0.28 parts by mole) of glycerin are mixed with 0.75 parts by volume of boron fluoride dietherate under nitrogen. 80 parts (0.28 parts by mole) of lauryl glycerin are then added dropwise over 40 minutes at 60 to 65°C while stirring and kept at this temperature for 4 hours. After separating off unreacted glycerin, a light brown liquid with good water-in-oil emulsifying properties is obtained.

Example 7

225 parts (24 parts by mole) of 1,4-butanediol are mixed with 2 parts by volume of boron fluoride acetic acid (37%) at 25°C under nitrogen. Then 1000 parts (3.09 parts by mole) of oleyl glycidyl ether are added dropwise over 45 minutes while stirring, during which the reaction mixture warms to 55°C. The temperature is increased to 65°C and kept at this temperature for 4 hours. After the reaction is complete, a medium brown liquid with very good water-in-oil emulsifying properties is isolated.

Example! 8

300 parts (3.3 mole parts) of chlorine are mixed with 100 parts by volume of boron fluoride-phosphoboric acid at 25° C under nitrogen. ^1/2 part (3.7 mole parts) of myristylglycidyl ether are added with stirring and the reaction mixture is heated to 160° C for 5 hours. After cooling, a colorless solid substance with very good water-in-oil emulsifying properties is isolated.

Example 9

60.2 parts (0.18 mole parts) of 1,2-ol-1-yloxymethylene-ethyl-1,2-diol are mixed with one volume part of boron fluoride etherate at 25°C under nitrogen. 50.2 parts (0.20 mole parts) of lauryl glycidyl ether are added dropwise over a period of 30 minutes while stirring, during which the reaction mixture warms to 50°C. After the dropwise addition is complete, heat to 65 to 70°C and keep at this temperature for 4 hours. The reaction product, a light yellow, clear liquid, shows very good water-in-oil emulsifier properties.

Example 10

92 parts of glycerine (1.0 mole part) and 268.5 parts (1.0 mole part) of oleyl alcohol are mixed with 1.3 parts of boronic acid ethyl etherate at 25°C under nitrogen. The reaction mixture is heated to 70 to 75°C with stirring and 92.5 parts (1.0 mole part) of epichlorohydrin are added dropwise over the course of 25 minutes. The temperature is then increased to 80°C and the mixture is allowed to react at this temperature for 4.5 hours. The mixture is then allowed to cool to 25°C, 44 parts (1.1 mole parts) of solid powdered sodium hydroxide are added with vigorous stirring and the mixture is stirred at 25°C for 15 hours. Finally, 2.8 parts of sodium methylate are added, the mixture is heated to 170 to 175°C on a descending condenser and kept at this temperature for 5 hours. After filtering the reaction mixture, you get a light yellow, clear liquid with very good water-in-oil emulsifying properties.

For example, the substance produced according to Example 5 has the following key figures:

State of aggregation Density at 50° C: Viscosity at 50° C: Color number: Refractive index at 50°

fluid
0.937
206 mPas
4 to 7
1.4620

Application

When producing emulsions, interface work must be carried out. As a rule, one phase is slowly added to the other phase at an elevated temperature (70 to 75°C) with good stirring. The temperature of the phase that is added should be 2°C higher than the initial phase. In the case of water-in-oil emulsions, water is best added in small portions to the fat emulsifier phase. Constant, not too vigorous, cold stirring of the emulsion is necessary, followed by homogenization. The type of stirring, the duration of stirring, the temperature control and the mechanics of homogenization are important here.

For example, a cream has the following composition:

Vaseline (C^-Cso-hydrocarbons saturated) Ozokerii (petroleum wax) Olive oil Caprin/caprylic acid triglyceride Isopropyl myristate Emulsifier according to the invention according to Example 5 Preservative based on p-hydroxybenzoic acid ester Perfume oil H ₂ O

15.0% by weight 5.0% by weight 10.0% by weight OK, 0% by weight 5.0% by weight 5.0% by weight 0.2% by weight 0.3 wt.% 49.5 wt.%

Emulsifying power and emulsifying numbers (water numbers)

Emulsifiers used

Emulsifying power with Vaseline

Emulsification number
with paraffin oil

Enmlsion stability

Emulsifier according to Example 1 250 1150 very good Emulsifier according to Example 5 275 1125 very good Emulsifier according to Example 7 245 930 very good Emulsifier according to Example 9 230 850 very good Wool wax 145 600 satisfactory Bstt acid pentaerythritol citric acid ester 210 645 satisfactory Glycerol monooleate 190 740 satisfactory Sorbitan monooleate 190 685 satisfactory Sorbitan sesquioleate 220 800 good Sorbitan dioleate 200 780 bad Emulsifier according to DE-AS 12 20 441, example 2 180 900 bad

Determination of the emulsification number (water number)

<WZ = water absorbed in g of 95 g paraffin oil and 5 g emulsifier). The water number gives an indirect overview of the emulsifying power of water-in-oil emulsifiers. The results should not be overestimated, because the water-in-oil emulsion depends on too many other parameters to be able to derive an assessment from the WZ alone. The WZ should only be viewed relatively, because the values obtained depend crucially on the method.

This is done as follows:

4 g of emulsifier and 76 g of paraffin oil DAB 7 are mixed thoroughly in a beaker using a magnetic stirrer (heat if necessary). 20 g of this mixture are placed in the mixing bowl of a food processor at room temperature and homogenized for 3 minutes with a whisk. The stirring speed is set to level 100 using a controller. The stirring speed is then increased to level 160 and 1 ml of water at room temperature is added every half minute. After 20 ml of water has been absorbed, the water addition is increased to 2 ml, and after 50 ml to 5 ml. When the cream slides in the mixing bowl and the water is no longer absorbed within about 2 minutes, then the optimal water absorption has been achieved.

Since the values vary (approx. 5-10%), the water number must be determined at least 2 to 3 times. The water number is obtained by multiplying the g of water absorbed (determined by weighing) by 5.

Determination of emulsifying power

A reliable quick test in the laboratory is to determine the emulsifying power using Vaseline as the oil phase: 35 g Vaseline and 3 g emulsifier are heated to 70°C in a porcelain bowl and the melt is stirred well. Add 72°C hot water in portions while stirring gently with a porcelain pestle by hand. The absorption of 62 g of water is rated with "Emulsifying power 100". (Accordingly, "Emulsifying power 200" means an absorption of 124 g of water).

If all parameters are kept constant, the values vary between 5 and 10%. The values in the table are averages from several measurements.

The table shows the superiority of the new water-in-oil emulsifiers in terms of their emulsifying power.

Emulsion stability (stability of creams)

Creams (water-in-oil emulsions) were prepared using the water-in-oil emulsifiers according to the invention according to the following procedure. Their stability was assessed after prolonged storage at room temperature (longer than 6 months), after testing for several weeks in a warming cabinet (at 140° C), in a refrigerator (at 6°) and in the so-called "rocking test". It can be seen from the table that the stability of the creams prepared using the emulsifiers according to the invention is very good.

Water-in-oil cream for stability testing

5.0 parts by weight of emulsifier 0.2 parts by weight of cetyl-stearyl alcohol 4.0 parts by weight of paraffin oil 35.8 parts by weight of vaseline 55.0 parts by weight of water 100.0

40 45 50 55 60 65

1 &igr; ' ■ 24 55 287 I Thermal stability of emulsifiers 5 Commercially available water-in-oil emulsifiers and emulsifiers prepared according to the invention were tested for
compared that they can be stored at low and elevated temperatures (drying cabinet 75" C) for 4 weeks
The results used in the following table were obtained: 10
15
20 Refrigerator Warming Cabinet
without with
H ₃ PO ₄ H ₃ PO ₄ i
ft
/
4 25 Soibitan sesquioleate ++
Glycerol sorbitan oleic acid ester ++ - &mdash;
Fatty acid pentaerythritol citric acid ester ++ + &mdash;
Citric acid distearyl ester mixture
Emulsifier according to Example 5 ++ ++ ++
++ = odorless = no discoloration
+ = still odorless = at most slight yellowing
- = slightly rancid = yellow to brown
&mdash; = unbearably rancid = dark brown 30 35 40

45 50

Claims (2)

Patent claims: 1. Use of products obtained by reacting saturated or unsaturated fatty alcohols with 10 to 22 carbon atoms or mixtures thereof in a first reaction stage with epichlorohydrin in a molar ratio of 1:0.5 to 1:1.5 and further reacting the glycidyl ethers thus obtained in a second stage with polyhydric alcohols containing 2 to 6 carbon atoms and 2 to 6 hydroxyl groups or their monoethers with fatty alcohols containing 10 to 22 carbon atoms in a molar ratio of glycidyl ether: alcohol such as 1:0.5 to 1:6.0 in the presence of acids or bases by adding the corresponding molar amount of glycidyl ether to the polyhydric alcohol containing the catalyst, within 5 to 60 minutes and then reacting the mixture within 2 to 8 hours, Defrosting points between 15 and 60°C and densities between 0.910 and 0.950, as emulsifiers in the cosmetic industry for the production of water-in-oil emulsions. 2. Use of products according to claim 1, which are obtained by a modified process in which the glycidyl ethers and the other reaction products are prepared in a single-stage reaction, whereby the fatty alcohols and epichlorohydrin in the stated molar ratios and the polyhydric alcohols also in the stated molar ratios, which in this case refer to epichlorohydrin, are reacted together in the presence of the acidic and then the basic catalysts and have thawing points between 15 and 60°C and densities between 0.910 in-d 0.950.